We explore design argumentation as a resource when teaching interaction design in a university setting. We propose that design argumentation can help bridge between practice-based design education and theoretical issues from university curricula. In this paper, we outline the idea of design argumentation and report on initial experiences from interaction design teaching activities. We discuss how this approach allows students to build up a shared and rigorous design vocabulary in order to formulate valid claims when arguing for and through their design work based on empirical, theoretical and material grounds.